1. Technical Field
The present invention relates to an ink jet printer that prints a predetermined character, an image, and the like by discharging fine particles (ink droplets) from a plurality of nozzles so as to form ink dots on a print medium.
2. Related Art
In general, such ink jet printers are not expensive and allow a high-quality color printed matter to be easily obtained. Accordingly, such ink jet printers have been widely spread into not only offices but also general users with the widespread use of personal computers, digital cameras, and the like.
In such ink jet printers, it is general that ink droplets are discharged from nozzles of an ink jet head while a movable body called a carriage, in which an ink cartridge and an ink jet head are integrally provided, is reciprocating on a print medium in a direction crossing a transport direction of the print medium so as to form fine ink dots on the print medium, thereby creating a predetermined printed matter. By providing the carriage with ink cartridges corresponding to four colors (black, yellow, magenta, and cyan) and ink jet heads for the four respective colors, not only monochrome printing but also full color printing can be easily performed.
In addition, in an ink jet printer in which a carriage is not used but a long print head having the same size as the width of a print medium is provided, it is not necessary to move the print head in the width direction of the print medium and so-called one pass printing is possible. Accordingly, high-speed printing becomes possible similar to an electrophotographic printer. In addition, an ink jet printer corresponding to the former method is generally called a ‘multi-pass type ink jet printer’, and an ink jet printer corresponding to the latter method is generally called a ‘line head type ink jet printer’.
Here, in the case when water-based ink is used in an ink jet printer, curving of a print medium after printing, so-called curl is a problem. In order to prevent such curl from occurring, a technique in which curl prevention liquid is coated on a surface of a print medium opposite a printing surface immediately after printing and then the print medium is caused to pass through a heat roll heater having heat sources disposed up and down so as to dry the print medium is used in an ink jet printer disclosed in JP-A-10-151733, for example. In addition, in an ink jet printer disclosed in JP-A-2005-178251, curl is prevented by providing a vapor generator, which uses heating or ultrasonic vibration, inside a roller serving to transport a print medium and applying vapor from a surface of the roller onto a surface of a print medium opposite a printing surface. In addition, in an ink jet printer disclosed in JP-A-2005-178252, a technique of detecting the humidity of a printing environment and controlling the amount of vapor generated in accordance with the environmental humidity is disclosed in addition to the ink jet printer disclosed in JP-A-2005-178251.
However, in the ink jet printers disclosed in JP-A-10-151733, JP-A-2005-178251, and JP-A-2005-178252, it takes time to dry a print medium and consumption of energy required for heating is large since curl prevention liquid or vapor is also applied on a print medium in addition to ink required for printing. In addition, even though there may be a print medium with no curl depending on a printing state, waste of energy is large in a point that curl prevention liquid or vapor is applied on all print media and the print media is dried.